Thermal Resistance Due To Fouling Deposits
Surface coatings can build on heat transfer surfaces during heat exchanger operation due to fouling. These add extra thermal resistance to the wall and may noticeably decrease the overall heat transfer coefficient and thus performance. (Fouling can also cause other problems.)
The additional thermal resistance due to fouling can be found by comparing the overall heat transfer coefficient determined from laboratory readings with calculations based on theoretical correlations. They can also be evaluated from the development of the overall heat transfer coefficient with time (assuming the heat exchanger operates under otherwise identical conditions). This is commonly applied in practice, e.g. The following relationship is often used:
- =
where
- = overall heat transfer coefficient based on experimental data for the heat exchanger in the "fouled" state,
- = overall heat transfer coefficient based on calculated or measured ("clean heat exchanger") data,
- = thermal resistance due to fouling,
Read more about this topic: Heat Transfer Coefficient
Famous quotes containing the words resistance, due, fouling and/or deposits:
“War is pillage versus resistance and if illusions of magnitude could be transmuted into ideals of magnanimity, peace might be realized.”
—Marianne Moore (1887–1972)
“It is due to justice; due to humanity; due to truth; to the sympathies of our nature; in fine, to our character as a people, both abroad and at home, that they should be considered, as much as possible, in the light of human beings, and not as mere property.”
—James Madison (1751–1836)
“Imagine believing in the control of inflation by curbing the money supply! That is like deciding to stop your dog fouling the sidewalk by plugging up its rear end. It is highly unlikely to succeed, but if it does it kills the hound.”
—Michael D. Stephens. “On Sinai, There’s No Economics,” New York Times (Nov. 13, 1981)
“Were all the worshippers of the gold calf to memorialize me and request a restoration of the deposits I would cut my right hand from my body before I would do such an act. The gold calf may be worshipped by others but as for myself I serve the Lord.”
—Andrew Jackson (1767–1845)